National Electrical Installation Standards

Standards as High as Your Own

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Friday, September 10, 2021

Question:

Hello Code Friends,

Do I need two grounding rods for a 100 ampere sub panel in my garage which will be used for feeding motor for a above ground pool.

Anthony Urbanik

A

Answer:

Hi Anthony,

There is not much information provided in the question that indicates where the panel is installed, or if it is installed in a single building supplied by a service or the panelboard is installed at a separate building or structure. It is difficult to read into what is being asked, but we'll give it a shot. If the panelboard is installed at a separate building and is the first disconnecting means for that separate structure as required by Section 225.31 and 225.32. Section 250.32(A) contains requirements for grounding electrodes at separate buildings or structures. All grounding electrodes present at the separate building or structure served shall be used to form the grounding electrode system. If no electrodes are present, then one shall be installed. If ground rods are chosen to be installed, then two must be installed unless a single ground rod does not exceed 25 ohms resistance to ground. See 250.53(A)(2) and the exception as applicable. If the panelboard is not in a separate building or structure, then the motor must be connected to an equipment grounding conductor of the branch circuit supplying the motor. The general equipment grounding requirements for motors of all voltages are  are provided in Part XIII of Article 430. This part of Article 430 refers to the applicable sections within Article 250.

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